Assuming all gases are at the same temperature and pressure, how many milliliters of hydrogen gas must react to give 49.0 mL of NH3? 3H2(g)+N2(g)→2NH3(g)

Question

I need to solve this problem, I am having a lot of trouble and this assignment is due tonight. 

Answer 1

You're told to assume the same temperature and pressure for the gases, so let's pick STP. At STP, gases occupy 22.4 L. That is useful to calculate the number of moles in 49.0 mL, but you don't need to do that for this question. 

 

We know the molar ratio of hydrogen to ammonia is 3:2. All you have to do is find the volume of hydrogen through the molar ratio.

 

Vol of H₂ = 3 mol H₂ x   49.0 mL NH₃

                     2 mol NH₃ 

= 73.5 mL H₂